1. Field of the Invention
The present invention relates to an electromagnetic x-y stage driver for a nano data storage system and a method for fabricating the coils of the same.
2. Description of the Related Art
Recently, the discovery of new microscopic phenomena of various atomic levels or the development of a data storage using a scanning probe microscope has been frequently accomplished. In particular, many magnetic devices using a Micro Electro-Mechanical System (MEMS) have been developed. Such magnetic devices include a magnetic compass, an electromagnetic scanner and an electromagnetic valve.
FIG. 1 is a schematic diagram illustrating a fine positioning apparatus with atomic resolution that is disclosed in U.S. Pat. No. 5,808,302. Referring to FIG. 1, a conventional fine positioning apparatus includes a voice coil motor (VCM) 417 for moving a sample 416 in the z-direction, a VCM 415 for moving a tip 413 in the x-direction and in the y-direction, a direct current (DC) supply 421, a data and control signal bus 424 and a central control unit 420.
The biggest problem of apparatuses using such a conventional fine positioning apparatus is a large amount of power loss. Generally, electromagnetic type apparatuses have large displacement but require large current for this displacement. Since electromagnetic type apparatuses using semiconductor manufacturing technology mostly use a thin coil of several microns through several tens of microns, it is difficult to achieve actuation with large displacement actually due to the large resistance of the coil, and the power consumption is large.
To solve the above problems, it is an object of the present invention to provide an electromagnetic x-y stage driver for a nano data storage system and a method for fabricating coils for the same, which are essential to development of nano storage devices using the SPM technology and through which coils can be fabricated to have a thickness of several tens to several hundreds of microns, thereby realizing actuation with large displacement and decreasing power loss.
Accordingly, to achieve the above object of the invention, there is provided an electromagnetic x-y stage driver for a nano data storage system. The electromagnetic x-y stage driver includes an x-y stage on which a medium for recording data is mounted; a supporting unit for elastically supporting the x-y stage, the supporting means comprising a plurality of driving beams provided at the corners of the x-y stage; an electromagnetic driver for providing mobility for the x-y stage in a first direction x and a second direction y orthogonal to the first direction x, the electromagnetic driver comprising a plurality of coils formed on the x-y stage and a plurality of permanent magnets for forming magnetic fields across the coils at fixed positions; a cantilever tip array fixedly provided above the medium to write data to or read data from each cell of the medium; and a plurality of stiffeners disposed around the x-y stage to connect the driving beams to each other, the stiffeners preventing the x-y stage from rotating.
In one embodiment, the medium is formed on the top of the x-y stage, and the coils are formed on the bottom of the x-y stage. In another embodiment, the medium is formed at the center of the top of the x-y stage, and the coils are formed around the medium on the top of the x-y stage. The supporting unit includes a supporting beam in the shape of a quadrilateral frame having four corners to which the driving beams are connected, and a stage base contacting the bottom of the supporting beam. Alternatively, the supporting unit includes a plurality of supports connected to the driving beams, respectively, and a stage base at which the supports are installed. Each driving beam includes an x-direction portion extending in the first direction and a y-direction portion extending in the second direction, and each stiffener is connected to a portion at which the x-direction portion meets the y-direction portion. Furthermore, each driving beam includes x-direction portions parallel to each other and y-direction portions parallel to each other so that it has the shape of a quadrilateral frame as a whole.
To achieve the above object of the invention, in one aspect, there is provided a method of fabricating a coil of an electromagnetic x-y stage driver for a nano data storage system. The method includes the steps of (a) forming trenches in a substrate using an Inductively Coupled Plasma Reaction Ion Etching (ICPRIE) method and then forming a passivation layer on the resultant structure using a thermal oxidation process; (b) filling the trenches with a metal; and (c) removing the metal exposed over the trenches using polishing, thereby completing a coil realized as the metal filling the trenches.
Preferably, the step (b) is performed using an electroplating method.
In another aspect, there is provided a method of fabricating a coil of an electromagnetic x-y stage driver for a nano data storage system. The method includes the steps of (a) forming trenches to at least a predetermined depth in a substrate using an ICPRIE method and then forming a passivation layer on the resultant structure using a thermal oxidation process; (b) depositing a metal film on the substrate having the trenches and the passivation layer so that only the top surface of the substrate is coated with the metal film and performing primary electroplating using the metal film as an electrode, thereby forming a first metal layer which does not fill the trenches; (c) etching the rear surface of the substrate to expose the trenches and performing secondary electroplating using the first metal layer as an electrode, thereby depositing a second metal layer to fill the trenches; and (d) polishing and removing the first metal layer, thereby completing a coil.